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Date:   Wed, 28 Nov 2018 09:48:05 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid frequent costly fsck triggers
Message-ID: <20181128174805.GB41969@jaegeuk-macbookpro.roam.corp.google.com>
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 <724de929-6ee1-3ad7-cfa7-6e80d4e7a3da@huawei.com>
 <20181128081035.GA41969@jaegeuk-macbookpro.roam.corp.google.com>
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On 11/28, Chao Yu wrote:
> On 2018/11/28 16:10, Jaegeuk Kim wrote:
> > On 11/28, Chao Yu wrote:
> >> Hi Jaeguek,
> >>
> >> On 2018/11/28 15:31, Jaegeuk Kim wrote:
> >>> If we want to re-enable nat_bits, we rely on fsck which requires full scan
> >>> of directory tree. Let's do that by regular fsck or unclean shutdown.
> >>
> >> Reviewed-by: Chao Yu <yuchao0@huawei.com>
> >>
> >> BTW, I have patch made some month ago...
> >>
> >> In order to detect nat_bits disabling, could we introduce one more flag for
> >> fsck?
> > 
> > Do we have a way to enable nat_bits very quickly in fsck?
> 
> For image with SBI_NATBIT_NEED_REPAIR flag, can we just check metadata and
> rebuild nat_bits based on verified nat blocks/journals?

I'm leaning to rely on full scan to enable nat_bits again. We may add a mount
count or timer to trigger fsck regularly?

> 
> Thanks,
> 
> > 
> >>
> >> >From 86e8bdb2faeec904944bb6621073f4f7de51cc2d Mon Sep 17 00:00:00 2001
> >> From: Chao Yu <yuchao0@huawei.com>
> >> Date: Sun, 9 Sep 2018 05:40:20 +0800
> >> Subject: [PATCH] f2fs: set specified flag after invalidating nat_bits
> >>
> >> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> >> ---
> >>  fs/f2fs/checkpoint.c    | 12 +++++++++++-
> >>  fs/f2fs/f2fs.h          |  3 ++-
> >>  fs/f2fs/node.c          |  3 +++
> >>  include/linux/f2fs_fs.h |  1 +
> >>  4 files changed, 17 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> >> index 7e17bb3dfcb1..f7fb14e0f5f9 100644
> >> --- a/fs/f2fs/checkpoint.c
> >> +++ b/fs/f2fs/checkpoint.c
> >> @@ -1226,13 +1226,16 @@ static void update_ckpt_flags(struct f2fs_sb_info
> >> *sbi, struct cp_control *cpc)
> >>  	unsigned long orphan_num = sbi->im[ORPHAN_INO].ino_num;
> >>  	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
> >>  	unsigned long flags;
> >> +	bool disable_natbits = false;
> >>
> >>  	spin_lock_irqsave(&sbi->cp_lock, flags);
> >>
> >>  	if ((cpc->reason & CP_UMOUNT) &&
> >>  			le32_to_cpu(ckpt->cp_pack_total_block_count) >
> >> -			sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks)
> >> +			sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks) {
> >>  		disable_nat_bits(sbi, false);
> >> +		disable_natbits = true;
> >> +	}
> >>
> >>  	if (cpc->reason & CP_TRIMMED)
> >>  		__set_ckpt_flags(ckpt, CP_TRIMMED_FLAG);
> >> @@ -1270,11 +1273,18 @@ static void update_ckpt_flags(struct f2fs_sb_info
> >> *sbi, struct cp_control *cpc)
> >>  	if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
> >>  		__set_ckpt_flags(ckpt, CP_QUOTA_NEED_FSCK_FLAG);
> >>
> >> +	if (is_sbi_flag_set(sbi, SBI_NATBIT_NEED_REPAIR))
> >> +		__set_ckpt_flags(ckpt, CP_NATBIT_NEED_FSCK_FLAG);
> >> +
> >>  	/* set this flag to activate crc|cp_ver for recovery */
> >>  	__set_ckpt_flags(ckpt, CP_CRC_RECOVERY_FLAG);
> >>  	__clear_ckpt_flags(ckpt, CP_NOCRC_RECOVERY_FLAG);
> >>
> >>  	spin_unlock_irqrestore(&sbi->cp_lock, flags);
> >> +
> >> +	if (disable_natbits)
> >> +		f2fs_msg(sbi->sb, KERN_NOTICE,
> >> +			"No enough space in CP area, disable nat_bits.");
> >>  }
> >>
> >>  static void commit_checkpoint(struct f2fs_sb_info *sbi,
> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >> index f0cedbe0c536..b55341c269b2 100644
> >> --- a/fs/f2fs/f2fs.h
> >> +++ b/fs/f2fs/f2fs.h
> >> @@ -1107,6 +1107,7 @@ enum {
> >>  	SBI_QUOTA_NEED_FLUSH,			/* need to flush quota info in CP */
> >>  	SBI_QUOTA_SKIP_FLUSH,			/* skip flushing quota in current CP */
> >>  	SBI_QUOTA_NEED_REPAIR,			/* quota file may be corrupted */
> >> +	SBI_NATBIT_NEED_REPAIR,			/* nat full/empty bitmaps need repair */
> >>  };
> >>
> >>  enum {
> >> @@ -1628,7 +1629,7 @@ static inline void disable_nat_bits(struct
> >> f2fs_sb_info *sbi, bool lock)
> >>  {
> >>  	unsigned long flags;
> >>
> >> -	set_sbi_flag(sbi, SBI_NEED_FSCK);
> >> +	set_sbi_flag(sbi, SBI_NATBIT_NEED_REPAIR);
> >>
> >>  	if (lock)
> >>  		spin_lock_irqsave(&sbi->cp_lock, flags);
> >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >> index e57add1e8966..0c6f8312a087 100644
> >> --- a/fs/f2fs/node.c
> >> +++ b/fs/f2fs/node.c
> >> @@ -2902,6 +2902,9 @@ static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
> >>
> >>  	cp_ver |= (cur_cp_crc(ckpt) << 32);
> >>  	if (cpu_to_le64(cp_ver) != *(__le64 *)nm_i->nat_bits) {
> >> +		f2fs_msg(sbi->sb, KERN_NOTICE,
> >> +			"Disable nat_bits due to incorrect cp_ver (%llu, %llu)",
> >> +			cp_ver, le64_to_cpu(*(__le64 *)nm_i->nat_bits));
> >>  		disable_nat_bits(sbi, true);
> >>  		return 0;
> >>  	}
> >> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> >> index 7196653833fa..1f3ae1504573 100644
> >> --- a/include/linux/f2fs_fs.h
> >> +++ b/include/linux/f2fs_fs.h
> >> @@ -117,6 +117,7 @@ struct f2fs_super_block {
> >>  /*
> >>   * For checkpoint
> >>   */
> >> +#define CP_NATBIT_NEED_FSCK_FLAG	0X00002000
> >>  #define CP_DISABLED_FLAG		0x00001000
> >>  #define CP_QUOTA_NEED_FSCK_FLAG		0x00000800
> >>  #define CP_LARGE_NAT_BITMAP_FLAG	0x00000400
> >> -- 
> >> 2.18.0.rc1
> >>
> >>
> >>
> >>>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> >>> ---
> >>>  fs/f2fs/f2fs.h | 6 +++++-
> >>>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>> index c28a9d1cb278..aa500239baf2 100644
> >>> --- a/fs/f2fs/f2fs.h
> >>> +++ b/fs/f2fs/f2fs.h
> >>> @@ -1621,7 +1621,11 @@ static inline void disable_nat_bits(struct f2fs_sb_info *sbi, bool lock)
> >>>  {
> >>>  	unsigned long flags;
> >>>  
> >>> -	set_sbi_flag(sbi, SBI_NEED_FSCK);
> >>> +	/*
> >>> +	 * In order to re-enable nat_bits we need to call fsck.f2fs by
> >>> +	 * set_sbi_flag(sbi, SBI_NEED_FSCK). But it may give huge cost,
> >>> +	 * so let's rely on regular fsck or unclean shutdown.
> >>> +	 */
> >>>  
> >>>  	if (lock)
> >>>  		spin_lock_irqsave(&sbi->cp_lock, flags);
> >>>
> > 
> > .
> >